A 38-year-old patient complains of a fever of 39°C, chills, profuse sweat, and dull lumbar pain that radiates into the suprapubic region. Objectively, muscle tension is observed in the lumbar region, percussion test in the lumbar region provokes painful sensations on both sides. Complete blood count shows leukocytosis of 12x109/L. General urinalysis revealed the following: proteinuria - 0.7 g/L, leukocyturia 15-20 in sight, bacteriuria of over 100,000 bacteria per 1 mL of urine What is the most likely diagnosis in this case?